The “Guerriero di Castiglione”: reconstructing missing elements with integrated non-destructive 3D modelling techniques

Accurately measuring an artefact of historical significance generally results in being able to extract information which is useful for evaluating what remains of the materials from a distant time. This allows scholars arrive at an exhaustive historical reading of the same artefact.Compared to the traditional measuring techniques, which can often be imprecise and complicated, 3D laser scanners measure the morphological characteristics of an artefact with extreme accuracy. Despite this, it is not always possible to choose the most appropriate sensors due to the geometric peculiarities, or indeed, the size of the object.The present work deals with two non-destructive analyses of an ancient stone sculpture, which for its morphology and size was scarcely compatible with the technical characteristics of either of the scanners used. Both scanners operate on the same technical principal, but are quite different from each other in terms of scale and precision. For these reasons, a complex 3D model (extremely appropriate given the original artefact) was draw out through a synergy of the two techniques.The virtual particularities of the model allowed it to be manipulated with the appropriate software. In fact, on the basis of qualitative parameters devised by researchers, it proved possible to reproduce the artefact’s geometric form, both virtually and in the form of physical models, obtained through non-conventional restoration methods (R.P. techniques).It has also been possible to verify the state of degradation of the surface of the stone caused by the traditional methods of applying cataloguing or storage information to it.Finally, the results achieved provide opportunities for further research on certain geometrical characteristics of the stone which, as highlighted by the elaboration on the virtual model, seem to be traceable to non-manual, perhaps mechanical, processes. Therefore, the historical considerations which derive from this fact call certain scholars into play.     

Galvanic removal of metallic wrought iron from marine encrustations

Historic shipwrecks frequently contain a large proportion of wrought-iron tools, fasteners, and other types of artefacts. Encrustations readily form around such objects in many marine environments. Depending on many factors, the iron objects inside these encrustations may be well preserved, completely disintegrated, or poorly preserved but still present. The latter type of encrustation is every conservator's nightmare because removing the encrustation yields merely a poorly preserved artefact still in need of extensive additional conservation. Neatly separating the artefact from its encrustation in order to obtain a natural mould for casting is generally impossible. Having encountered this problem many times, the authors began to experiment with the extraction of metallic iron from poorly preserved encrusted artefacts using galvanic dissolution. Data on rates of dissolution were gathered for three experimental configurations. The results of a test conducted on an encrusted artefact were promising, but inconclusive.     

Quantifying the Size of Artefact Assemblages

Stone artefacts are broken, burnt and weathered. Processes such as these may act differentially across categories, and will therefore affect interpretations of assemblage size and composition. This paper advocates a more detailed consideration of abundance estimates in artefact analyses, being guided by the understandings built up in archaeological studies of fauna, and begins the process by developing some basic units of measurement for counting flaked stone.     

The decomposition of starch grains in soils: implications for archaeological residue analyses

Recent research involving starch grains recovered from archaeological contexts has highlighted the need for a review of the mechanisms and consequences of starch degradation specifically relevant to archaeology. This paper presents a review of the plant physiological and soil biochemical literature pertinent to the archaeological investigation of starch grains found as residues on artefacts and in archaeological sediments. Preservative and destructive factors affecting starch survival, including enzymes, clays, metals and soil properties, as well as differential degradation of starches of varying sizes and amylose content, were considered. The synthesis and character of chloroplast-formed ‘transitory’ starch grains, and the differentiation of these from ‘storage’ starches formed in tubers and seeds were also addressed. Findings of the review include the higher susceptibility of small starch grains to biotic degradation, and that protective mechanisms are provided to starch by both soil aggregates and artefact surfaces. These findings suggest that current reasoning which equates higher numbers of starch grains on an artefact than in associated sediments with the use of the artefact for processing starchy plants needs to be reconsidered. It is argued that an increased understanding of starch decomposition processes is necessary to accurately reconstruct both archaeological activities involving starchy plants and environmental change investigated through starch analysis.     

Variable Selection in Artefact Compositional Studies

In artefact compositional studies, the selection of variables to use in analysis is unavoidable. Given this ubiquity, surprisingly little attention has been paid to ways in which variables might be selected. After arguing the case for the importance of variable selection, two systematic approaches to making a choice, which have had little or no application in archaeometry, are discussed and illustrated. One, based on the use of principal components, is appropriate if structure in the data is not known. The other, based on the use of classification trees, is applicable when there are known or assumed groups in the data.     

Quantifying artefacts over time: Interval estimation of a Poisson distribution using the Jeffreys prior

This paper presents a new method for estimating the amount of an artefact class in use at a given moment in the past from a random assemblage of archaeological finds. The method is based on the use of simulation, since an analytical solution is computationally impractical. Estimating the number of artefacts in use at any time t is shown to follow a Poisson distribution, which allows for credible intervals to be established using the Jeffreys prior. This estimator works from minimal assumptions about the dating and duration of finds, as well as the intensity of collection, and is applied to coinage from four Roman‐period sites excavated by the Roman Peasant Project (2009–14). The result provides an estimation of the abundance of material according to an interval of certainty.     

Measuring reduction in stone tools: an ethnoarchaeological study of Gamo hidescrapers from Ethiopia

Stone tools were knapped, not built. This truism means that tools were reduced from larger pieces in the production process. But many tools were further reduced in use, to repair damage or as edges dulled. Reduction reduced size (trivially), but also changed the proportions among tools' elements or dimensions. Such allometric variation (change in proportion as a function of change in size) is useful to estimate the degree of reduction that tools experienced. Reduction itself is a measure of curation, a theoretical concept of great interest in lithic studies and Paleolithic archaeology. To determine the reduction that archaeological tools experienced, we must compare their size and proportions at first use to the same properties at discard that we directly measure. By now many size estimates can be made from discarded tools. Some are experimentally tested but few are validated using direct ethnoarchaeological controls. We validate two allometric reduction measures—ratios of plan area to thickness and of an estimate of original to discarded volume—against direct measures of use and reduction in ethnographic Gamo hidescrapers from Ethiopia.     

Oldowan reduction sequences: methodological considerations

Transport of resources is a major feature of Oldowan hominin technological adaptations. Comparisons between different Oldowan localities often employ measures of transport that are based on artefact attributes as proxies for the intensity of raw material utilization. The Technological Flake Category system [Toth, N., 1985. Oldowan reassessed: a close look at early stone artifacts, Journal of Archaeological Science 12, pp. 101–120] has been used extensively to infer the relative intensity of lithic reduction within Oldowan assemblages. Here we use a large experimental sample to test the relationship between a flake's stage in a reduction sequence and various quantitative attributes. We demonstrate how many previously described attributes are affected by initial core size. We then develop a multiple linear regression model that incorporates several variables to predict the placement of a flake within a generalized reduction sequence. The model is then applied to Oldowan assemblages in the Koobi Fora Formation which explores the strengths and weaknesses of different methods of investigating reduction intensity on an assemblage level.     

Locating the origins of wood resources: a review of dendroprovenancing

Dendroprovenancing studies have been shown to have historically been initiated on the use of oak in art-historical contexts, but are now employed on a much wider range of species and artefact types, particularly in relation to ship remains. The commonest methodology is to compare individual site chronologies with a network of other chronologies, and to recognise trends in the geographical distribution of strong matches, suggesting the likely source area of the material. Other studies may look at the matching of individual timbers to draw similar conclusions. It is shown that ecological and genetic factors may strongly influence individual matching results and that ring-widths may therefore be considered a somewhat crude means of provenancing. Additional chemical and genetic markers are discussed, although these are unlikely to become routinely used in the near future.     

Modelling small-arms projectile distribution on eighteenth- and nineteenth-century battlefield sites

The application of Geographic Information Systems (GIS) technologies to archaeological investigations continues to provide new perspectives on historical events. Applied to battlefield archaeology, GIS analysis offers an efficient means of predicting potential artefact distribution across a conflict landscape. The approach proposed in this piece allows a user to test historical engagement scenarios within a desktop computing environment utilizing a customized GIS application. The study was intended to develop a framework that allowed for the input of quantifiable parameters in order to illustrate potential artefact patterning. The framework consists of two components, the trajectory model and the methodology for implementing it. Using this coarse-grained approach, it is our contention that small-arms projectile distribution can be estimated for a single engagement, and in doing so provide a more comprehensive view of potential artefact patterning than using KOCOA (Key Terrain, Observation and Fields of Fire, Concealment and Cover, Obstacles, Avenues of Approach/Withdrawal) terrain analysis or historic research alone. As an initial example to illustrate the efficacy of our model, this study uses data and parameters from the 1777 Battle of Ridgefield, Connecticut landscape as a test case.     

‘Would I were in an alehouse in London!’: a finds assemblage sealed by the Great Fire from Rood Lane,City of London

During the development project at 20 Fenchurch Street in the City of London, archaeological excavations were undertaken adjacent to Rood Lane. This uncovered part of a 16th- to mid 17th-century brick built cellar which had collapsed sealing in situ pottery, glass, clay tobacco pipes and a stove tile, an event interpreted as the result of the Great Fire of London in 1666. The composition of this artefact assemblage suggests it was derived from a property used to providing large-scale entertainment, with a high proportion of the material associated with drinking. This article situates this group within the context of other similarly dated victualling establishments from the City of London.     

Mano size,stable carbon isotope ratios,and macrobotanical remains as multiple lines of evidence of maize dependence in the American southwest

While the level of agricultural dependence affects many aspects of human adaptation, estimating levels of dependence on maize through traditional archaeological techniques is problematic. Here we compare various measurements of manos (e.g., grinding surface area), macrobotanical evidence of maize use, and human collagen stable carbon isotope values from six regions of the American Southwest, encompassing 16 phases, as a means of assessing the power and limits of each approach for considering agricultural dependence. The analysis of each data class is considered separately, taking into account formation processes and arguments linking data and inferences. Correlations among the three data classes suggest that mano area and maize ubiquity can be considered ordinal measures of agricultural dependence, but Southwestern stable carbon isotope data have the analytical potential only to discriminate between little or no maize use and substantial maize use. The formation processes and linking arguments associated with each method must be considered when multiple lines of evidence are integrated in order to make sound behavioral inferences. Our results suggest that there were at least three patterns in the adoption of farming in the Southwest: early substantial use followed by continuous increasing maize dependence, initial intensive dependence with little change in later periods, and a long period of minor use followed by substantial dependence.     

MAGNETIC SUSCEPTIBILITY USED IN NON-DESTRUCTIVE PROVENANCING OF ROMAN GRANITE COLUMNS

Magnetic susceptibility provides a rapid, cheap and non-destructive method of in situ characterization of archaeological artefacts containing magnetic minerals, and can be used as an aid to geological provenancing. Three hundred and sixty-three Roman granite columns were measured by this method and results show clear groupings and similarities with potential granite sources in Italy, Turkey and Egypt. Magnetic susceptibility measurements must be made on representative, unweathered surfaces of rocks and artefacts, and corrected for object size and surface relief according to manufacturers’recommendations. In addition, corrections for column curvature have been derived for use with measurements made on columns.     

The material culture of the modern world

SUMMARY: We discuss results of a content analysis of material culture articles in Post-Medieval Archaeology in the context of the development of historical archaeology as a discipline. We conclude that the journal remains an important outlet for detailed field reports, but in recent years, influenced by social and anthropological theories, the discipline has matured and articles have changed from antiquarian artefact presentations to contextualized material culture studies. Expansion of the journal’s temporal frame to include the recent past has so far had little effect, but the journal has benefited from the broadened international range of articles and the intellectual and theoretical backgrounds they convey.     

Photographic methods to detect colourants in archaeological textiles

Protocols for photography of archaeological textiles to detect components of differing chemistry that are indicative of colourants were developed. Parameters of light source, camera distance, filter type, film type, film speed, and aperture size were evaluated for visible, UV-reflectance, UV-fluorescence, and infrared photography. Using these techniques facilitates selective sampling for further analysis that maximizes critical data acquisition while minimizing destruction of the artefact. Hence, forensic photography of archaeological perishable materials should be regarded as a precursor to destructive analytical methods.     

An Independent Confirmation of the 4 ka Antiquity of a Beeswax Figure in Western Arnhem Land,Northern Australia

Critical to any chronology is reliability in the determination of age for a distinctive artefact that is related to other components in a series. Therefore, the independent testing and verification of the antiquity of an apparent anomalous measurement for an old beeswax figure in northern Australia is of fundamental interest in rock art studies. Replication of the radiocarbon dating process has confirmed that one exceptional figure in early X‐ray style at the Gunbilngmurrung site in western Arnhem Land is indeed c. 4–4.5 ka. The result also confirms the great antiquity of paintings over which the beeswax was applied.     

THE RELATIONSHIP BETWEEN LITHOLOGY,FLAKING PROPERTIES AND ARTEFACT MANUFACTURE FOR AUSTRALIAN SILCRETES*

Mechanical properties of Australian silcrete strongly influenced raw material selection and artefact manufacture. Microcrystalline silcrete, with high compressive and tensile strength, is suitable for blade tools requiring fine retouch. Fine‐grained silcrete (high compressive strength but lower tensile strength) was often used for blade‐based implements, but is more susceptible to edge fracturing. Medium‐grained silcrete has poor flaking properties (low compressive and tensile strength) and was often used for flake manufacture. Thus material determinism can explain much of the variability in silcrete artefact morphology and assemblage composition. Silcrete compressive strength is positively correlated with percentage of microcrystalline matrix and negatively correlated with average grain size, so hand lens examination of a silcrete sample can give a good indication of its likely flaking quality.     

Experimental characterization of the constitutive materials composing an old masonry vaulted tunnel of the Paris subway system

A significant proportion of the Paris metro tunnels comprise a masonry vault built out of stone blocks and mortar joints, and sidewalls and slabs made of unreinforced concrete. In order to provide the necessary data for future structural evaluation, an extensive laboratory testing programme has been conducted to characterize the materials of the tunnel separately, i.e., mortar, stone, and concrete. The tests, carried out on specimens taken from cores extracted from a 1930s tunnel, enabled to determine the mechanical properties, including direct tensile, shear strength, and mode I fracture energy, as well as the properties of the stone-mortar interface. Results show that the masonry mortar joints could reach 10 cm in width, and that blocks of stone varied in composition and porosity, thus producing a wide range of mechanical properties. The concrete was composed of large-sized aggregates and showed low stiffness and strength. Based on these experimental results, ratios between mechanical characteristics are hereby proposed. Perspectives on the use of this experimental data in a finite element model are then discussed.